Diabetes is an epidemic afflicting 25 million Americans and nearly 350 million persons world-wide. Diabetic cardiomyopathy (DCM) is a cardiac pathology presented in many of those afflicted by diabetes, which contributes to a disproportionate risk of heart failure. Heart failure in part stems from the dysfunctional regulatin of calcium (Ca2+) in cardiomyocytes. Ca2+ plays a critical role in the excitation and mechanical activity of cardiac cells and pathogenic alterations its signaling pathways increase the propensity for dangerous arrhythmias. Reduced sarcoplasmic reticulum (SR) Ca2+ content is a major contributor to DCM, and deficient Ca2+ uptake by the sarcoplasmic reticulum Ca2+ ATPase (SERCA) is partially at fault. The complex interplay between SERCA, its endogenous inhibitor, phospholamban (PLB), and protein kinases in regulating SR content and Ca2+ signaling complicates our understanding of DCM. To this end, species- and DCM-specific mathematical models of Ca2+ signaling in cardiomyocytes enable the integration of diverse experimental probes of molecular-and cellular-level aspects of pathological PLB/SERCA function. In Aim 1, the molecular basis of PLB binding to SERCA and identify targets for increasing ATPase activity will be explored using molecular dynamics simulations. In Aim 2, the impact of enhanced SERCA uptake in restoring normal cardiac function, including the effects of CaMKII and beta-adrenergic stimulation, using a cellular model of Ca2+ signaling and phosphorylation will be examined. In the short term, successful completion of these aims will yield insight into precise control of SERCA by tuning the PLB interaction, thereby potentially yielding small-molecule targets to treat diabetic cardiomyopathy. In the long term, molecular and cellular insight into dysfunctional calcium regulation provide a mechanistic insight into diabetic cardiomyopathy and heart failure, in general.